Abstract: Climate warming affects the structure, function, and environmental attributes of grassland ecosystems. However, the response of trace element concentrations in grassland soils and plants to climate warming remains poorly understood. Here, we investigated the effects of short-term warming on Agropyron cristatum and Achnatherum splendens biomass, trace element concentration, and soil enzyme activities in a subalpine grassland in the central Qilian Mountains using an open-top chamber (OTC) experiment. The results showed that warming treatment significantly elevated aboveground biomass (AGB) (117.0%) and belowground biomass (BGB) (64.1%) of A. cristatum and AGB (112.5%) of A. splendens. The concentrations of Cu, Fe, Mo, Co and V in belowground parts of A. cristatum, Cu and Mo in aboveground parts and Ni in belowground parts of A. splendens under warming treatment were significantly higher than that in control, while Zn in belowground parts of A. splendens had the opposite trend (P < 0.05). Alkaline protease (30.6%) in 0–10 cm soil, Amylase (30.9%), alkaline protease (23.7%) and urease (57.2%) activities in 10–20 cm soil of A. splendens under warming treatment were significantly decreased than that in control (P < 0.05). Structural equation models indicated that warming negatively contributed to soil enzyme activities, both directly and indirectly (through its influence on relative humidity, soil pH and, in particular, trace element concentrations). Our results highlight the migration and cycling processes of trace elements in subalpine grassland ecosystems and their environmental behavior under climate warming.

Key words: open-top chamber, forage grasses, micronutrients, potentially toxic elements, subalpine grassland ecosystem